Macherey-Nagel test strips for chloride, in one presentation.
91321
A semi-quantitative test strip for chloride, the salt anion — not to be confused with chlorine. Dip it, wait the stated time, and compare the pad against the colour scale on the tube.
Chloride is what pits stainless steel, what tells you seawater has reached a coastal well, and what accumulates in any water that is recirculated and evaporated. It is not removed by any ordinary filter.
A strip gives a range, not a figure. That is enough for the great majority of decisions — dose or do not dose, discharge or hold, keep running or stop — and it gives the answer where the sample is, in about a minute, with no instrument to calibrate and nothing to carry back to a laboratory.
When a number has to be defensible — a regulatory report, a dispute, a limit you are close to — a photometer or a laboratory method is the right tool. The strip's job is to tell you whether you need one.
Chloride and chlorine are different measurements answering different questions; a water can be high in one and zero in the other.
Supplied in one presentation.